Conventional neutron detectors generally include a sealed vessel containing a neutron sensitive gas, such as 3He or BF3, and an electrically charged wire having leads which extend outside of the vessel. In operation, incident neutrons react with the gas and produce charged particles. The charged particles change the electrical potential of the wire. A measurement system coupled to the charged wire measures the electrical pulses and uses this information to indicate the presence of neutrons. These types of neutrons detectors are usually undesirably bulky and are associated with poor sensitivity resulting from, for example, electronic noise.
Attempts have been made to produce more portable neutron detectors using semiconductors. For example, 3He is diffused into a semiconductor substrate and used in the detection of neutrons. Neutrons react with the 3He gas and produces hole-electron pairs in a depletion layer within the semiconductor. The hole-electron pairs produce output electrical pulses which appear at the output terminals of the detector. The electrical pulses are utilized for detecting neutrons.
Semiconductor-based radiation detectors generally have a single-crystal substrate with a p-n junction or a Schottky junction. An inverse bias is applied to the depletion layer. When radiation in the form of neutrons, gamma-rays, X-rays, electrons, protons, etc. are absorbed by the material, electron-hole pairs are created. These charges give rise to a current that is a measure of the intensity of the radiation flux detected by the detector.